


you're mine

by adozencaptains



Category: Supergirl (TV 2015)
Genre: Angst, Cheating, F/F, Possession
Language: English
Status: Completed
Published: 2017-08-05
Updated: 2018-02-18
Packaged: 2018-12-11 14:02:38
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,836
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11715864
Author URL: https://archiveofourown.org/users/adozencaptains/pseuds/adozencaptains
Summary: “Yousaid,” Kara insists, balling her hands into fists by her side. “You said, Alex, that we would be -”“Together forever, yes, Kara, but I wasfourteen years old! Sisters say that to each other! Best friends say that to each other! That’s what we are,” Alex feels her voice catch at the end.





	1. 1

**Author's Note:**

> Unbetaed.

“You said you’d be mine,” Kara starts slowly, confused and frustrated and simply upset, “ _forever_.”

“We were - Kara, we were _kids_.” Alex throws her hands up, imploring Kara to see reason. Her heart was breaking with the way Kara was looking at her. “You can’t expect me to - we were just children. It was just a -”

“A joke? A lie?” Kara snaps. A flush grows on her cheeks, angry and unbidden. “You were just lying to me?”

“What do you want me to say?” Alex growls.

This wasn’t how their night was supposed to go. They were supposed to go to dinner, a nice restaurant that Alex made reservations for, which they definitely missed by now. Then they were going to go out for ice cream and come back to Kara’s for movies and popcorn before Alex could finally tell her that she had proposed to Maggie. Instead, _somehow_ that little tidbit of information had come out before they had even left Kara’s apartment.

Alex didn’t know what to expect when she told Kara about the progression of her relationship with Maggie, but this surely wasn’t it. Excitement, she expected, maybe even a bit of confusion and worry about it moving so quickly. But anger? Hurt? Betrayal? Alex didn’t know what to do with those. She wasn’t prepared for this.

“You _said_ ,” Kara insists, balling her hands into fists by her side. “You said, Alex, that we would be -”

“Together forever, yes, Kara, but I was _fourteen years old_! Sisters say that to each other! Best friends say that to each other! That’s what we are,” Alex feels her voice catch at the end. She can’t look at Kara, but she does.

Kara’s eyes are narrowed, and there’s a cut to her jaw that draws Alex’s eyes in - she’s furious. She more upset than she’s been in a very long time, and Alex doesn’t know what to do with that information.

“You. Said,” Kara says through clenched teeth. Her eyes are hardened, like blue steel, and her voice is gruff, like she can hardly force the words out of her mouth. “And now - you’re going to marry _Maggie_?”

“I love her!” Alex cries, and her voice breaks as she chokes back a sob. Why does she feel like she needs to defend her decision from Kara? Alex wraps her arms around herself, closing her eyes. “I love her,” she repeats.

“She’s a human, Alex! She’s a human, and - and, and you said you were _mine_!” Kara’s voice is full of equal parts indignation and disbelief. “I thought you loved me.”

“I do!” Alex snaps her eyes open, focusing them on Kara, who is a lot closer than she was a moment ago. Alex takes a step back. “I do, Kara.”

“Then why are you marrying her?” Kara tilts her head, all the same confusion she had as a naive and scared twelve year old on a different planet with only strangers to keep her company. “You said you were mine, and now you’re marrying her.”

Kara can’t stop saying that, and Alex can’t stop remembering.

She was fourteen, and Kara had been on Earth for a more than a year and a half. It had been a stressful transition for the family, but it tapered off as Kara learned more of the culture and customs of her new planet. It had been a stupid storm that terrified Kara more than any other, and when she crawled into Alex’s bed, shaking and sobbing, Alex had been helpless but to comfort her.

She said every soothing thing she could think of; she sang songs, told her stories from her childhood, stupid jokes that usually made her laugh, but nothing worked. Kara eventually migrated down and laid her head on Alex’s chest, clutching desperately to her for hours until the sun rose and neither of them had slept. Jeremiah let them skip school that day, telling Eliza they were both sick, and exhausted and yawning, Alex still dragged her surfboard down to the beach, where Kara huddled on a beach towel and chewed celery sticks while she watched her. 

When the waves carried her in one last time, Alex planted herself on the towel beside Kara, scratching absently at her rash guard, squinting up at her foster sister.

“Why was it so bad last night?” Alex had asked.

“I lost everyone and everything,” Kara whispered, wiping her nose. “Now I have no one and nothing.”

“You have me,” Alex offered, nudging Kara’s thigh until she laid down next to her. She laced their fingers together. “Forever, if you want.”

Kara didn’t say a word, simply nodded and shuffled closer to lay her sandy head on Alex’s shoulder.

That moment on the beach startled it all, and it spiraled out of control from there. How often Alex reminded Kara that she was hers - it surely passed the limit of sisterly consolation. It was odd, Alex knew that, but it brought them both a comfort that nothing else could. It didn’t bother her that no one else would understand because they didn’t _need_ to understand. It was for Kara and Kara alone.

When Kara was scared and needed something to ground her, when Alex was lashing out at the world because of stress, when they lost Jeremiah and the family grew smaller, when Alex’s first boyfriend kissed her and left a giant hickey on the side of her neck, when Kara accidentally broke a boy’s nose when he tried to kiss her - it was almost as if every memory of her childhood had been tainted by it. _I’m yours, Kara, always_. How often had she said it to her?

But it was when they kissed - sixteen and tipsy at a beach party - that had the most resounding effect. Kara was quiet, kept to herself, and Alex found her by the water’s edge about a mile down from the bonfire, digging her toes into the sand with her hand buried in the cuffs of her sweatshirt. Alex had a strong buzz going, but she was coherent enough to know something was wrong and pulled Kara into a hug. They hugged for a long time, and when Kara’s lips pressed against Alex’s neck the first time, she thought nothing of it. Until there was a second time, a third time, and on the fourth time, Kara’s tongue brushed the skin, making Alex shiver.

“What - are you doing?” Alex asked, but she didn’t move to stop Kara, or move at all really. Kara’s nose brushing her jaw made her shudder, but she stood stock still.

“Matt said - he told Brandon - he said he was going to make you his tonight,” Kara whispered, fingers pressing into Alex’s waist tightly. “Are you - will you - _Alex_.”

Alex swallowed, urging her hands to move, and she rubbed comforting circles against Kara’s back. “That’s just what guys say to each other when they want to sleep with girls.”

“No -” Kara pulled back abruptly, her face distraught, eyes searching. “Are you going to let him make you - are you going to be _his_?”

Alex snorted, a lopsided smile pulling at her lips as she pushed some of Kara’s hair behind her ear. “No silly. I told you - I’m yours. Always. No boy is going to ever change that. Ever.”

“Take me home?” Kara has asked, eyes wide with a kind of internalized fear Alex would never begin to understand.

So Alex did. And that night, instead of Matt Kinsey, Alex gave her first time to Kara, in the treehouse in the backyard where she had first learned to tolerate and then love the other girl. The old pine wood was hard and unforgiving under Alex’s back, but Kara’s gentle hands and flushed cheeks made it better. When the air became too brisk, Kara covered Alex’s body with her own, radiating body heat and something else too heavy for Alex to process at the time.

“You’re mine,” Kara murmured, lacing their fingers together and bringing their hands above Alex’s head. She kissed Alex, let Alex bite hard at her lips and grind desperately against her thigh with a keen moan. “Always.”

“Always. Promise,” Alex gasped, body tense with desire and lust. “Kiss me again.”

They had kissed until the sun came up, cementing Alex’s promise into the spaces between their naked bodies.

Alex was fourteen when it started, sixteen when it mattered most, and now she’s twenty-eight and wholly unprepared to deal with the consequences.

“I don’t know,” Alex croaks, eyes darting to the kitchen, “what you want me to say. I don’t know how to fix this. I’m sorry, Kara. I don’t know.”

“Say no,” Kara says like it’s the most obvious thing in the whole world. She takes a step toward Alex and then another, and then they’re almost touching. “Tell Maggie you can’t, you won’t. You’re not hers to have.”

“I’m not a freaking _object_ ,” Alex cries, almost hysterical. The whole situation is overwhelming, and she doesn’t know how to process her emotions and thoughts.

“I know,” Kara says patiently, and Alex doesn’t flinch when the back of Kara’s hand strokes her cheek. Her fingers press against the underside of Alex’s chin, strong against her jaw, and the thumb of her other hand comes up and wipes the tears from her face. “You’re Alex. You’re all I have in this world.”

“I know. I know.” Alex doesn’t sob; she cries silently in Kara’s hands.

“I love you,” Kara says quietly, and her lips quick at the end. Her eyes are soft now, and Alex could drown in them if she wanted to.

“I love you too.”

“Don’t marry her,” Kara whispers, and she kisses Alex’s left cheek, then her right. “Please don’t marry her.”

“I - I love her, Kara,” Alex says, and when Kara kisses her forehead, her eyes slip closed of their own accord. How soft her lips are, how they warm her body with their touch.

“Like you love me?” Kara counters, her voice void of any snark. Her lips brush Alex’s, completely still, and she exhales softly, her words hardly a whisper, “You’re mine. You promised.”

Kara catches Alex’s sob, her anguished _I know_ with her next kiss, a harsh press of her lips, desperate and urgent. Alex meets her kiss for kiss, lets Kara lick hotly into her mouth, clutches at her jacket like it’s the only thing keeping her grounded, when in reality, she knows it’s Kara’s hands. They cradle her face something fierce, reverent and gentle, like she is something fragile and worth handling with care. Kara doesn’t hold her like she could break, but she holds her like she is delicate and capable of disappearing right before her eyes. The difference, Alex has learned over the years, makes all the difference in the world.

_I know I’m yours. I know I promised. I know, I know._

“We can’t,” Alex says between kisses, even as Kara is walking them back toward her bedroom, lowering her onto the bed.

“We already did,” Kara points out somewhere between taking Alex’s shirt off and shucking her own pants to the floor beside it.

“I have a girlfriend - a _fiancée_ ,” Alex protests halfheartedly even as her hands scramble to help rid Kara of her shirt and bra.

Kara rips Alex’s bra apart at the front, dropping to her knees without preamble and tearing Alex’s underwear from her legs with her _teeth_. “Had,” she counters helpfully. “Should I stop?”

Alex’s chest heaves with the force of her breath, flushed red and nipples hard. Her hands had twisted themselves into the sheets in anticipation at the sight of Kara between her knees, and every rational thought had just about left her mind the moment Kara’s teeth scraped her hip.

There had been so many years, so many lonely nights when Alex had imagined a scenario not unsimilar to the one she’s found herself in - ones where Kara made her prove her devotion for all the years she strayed, ones where Kara’s tears mixed with her own as they recounted that night all those years ago, ones where she apologizes and Kara apologizes and together they right the wrong that had become their lives - and yet, none of those could possibly compare to the reality of feeling Kara’s fingers laced with hers once more as Kara’s lips paint promises of love across her sex, her tongue tracing her solemn vows against her swollen flesh, blue eyes watching her, unabashed, unembarrassed, and unapologetic.

“No,” Alex says, shaking her head. “Don’t stop.”

She has Maggie, a chance at a real relationship with someone who really cares about her. She has a woman that loves her, wants to spend the rest of her life with her. But she has Kara too, and Kara was here first. Kara wanted all of that too. Kara staked a claim to her first, laid waste to any and all reservations Alex might’ve had about possession when she first whispered _you’re mine_ against her naked breast bone in the treehouse behind her house. Alex hadn’t know she was offering her heart until Kara plucked it out of her hand and never gave it back.

For years, Alex denied the very truth in front of her, argued with herself and justified a very stupid night on very stupid teenage hormones and poorly-reigned impulsive decision-making. Why had she said it if she hadn’t meant it? Why did she let Kara touch her if she didn’t like her, didn’t love her, didn’t absolutely want her to?

“Alex,” Kara says in a soft voice, pressing a wet kiss to the inside of her thigh. The one word holds so much weight spoken from Kara’s lips, and the sound of it makes Alex shudder.

Years wasted. 

_You’re mine._

Denial.

_You’re mine._

Fear.

_You’re mine._

“I’m yours,” Alex gasps, reaching for Kara with a strangled moan when Kara’s fingers press inside of her, blue eyes watching, watching, watching.

_Always._


	2. chapter 2

**Summary for the Chapter:**

> Been a while, oops. Getting back in the swing of writing. 
> 
> Aftermath of chapter 1.

Alex tells Maggie. She has to, she knows that, but it doesn’t stop her from wanting to hide in the hole of misery and shame she dug for herself. So she tells her, and Maggie leaves.

There are copious amounts of tears - on both their parts - and Alex wants nothing more than for Maggie to stay. It’s selfish of her, to think about _asking_ Maggie to stay - if they could work some kind of relationship with Kara in the picture. How it would work, Alex doesn’t know, but since she doesn’t ask Maggie, she’ll never know. She wants them to work, for Maggie to just stay, but Maggie says she can’t compete with Kara and Alex doesn’t understand until she does.

It’s not that Kara is the most important person in her life - she is undoubtedly, but Maggie knew that going in - and it’s not that Kara had feelings for her first that Alex clearly reciprocated - which she did and Maggie knows they have history - but it’s how Kara literally fell from the stars to love her. How planets imploded and the galaxy twisted and the stars moved to make way for Kara, to bring her to Earth, to the Danvers, to Alex’s fucking backyard - there is no greater love story than that, and Maggie understands it long before Alex does.

Maggie is more understanding than Alex could’ve ever hoped any partner of hers would be when they’ve found out that they’ve been cheated on and ultimately left for said person. That it’s Kara can’t be any easier. Maybe Maggie understands because she, too, had cheated before. Maybe she understands because this is all so very new for Alex, not just women but serious relationships.

Alex apologizes and Maggie does too, and before she leaves, they kiss one last time. It’s bittersweet and tastes of salty tears, some of regret, some of sadness, but most of love. Alex doesn’t deserve that, and she cries long after Maggie has left her apartment. Body-wracking sobs and ugly wheezing, and Alex tries to remember what it’s like not to be a terrible person.

When Kara stops by, her supersuit feels unusually awkward and rough beneath Alex’s fingertips and her cape too brittle and itchy. Alex begs her to take it off. It falls from her body the way cloth should fall from a goddess, bringing tears to Alex’s eyes with every inch of skin exposed until she stands bare before her. Kara’s skin is soft than anything Alex has even felt when she clings to her, and for once, she’s absolutely grateful for it.

She holds to Kara as tightly as she can, and Kara doesn’t ask what she’s crying about. Alex supposes she must know, that there can’t be that many conclusions from which Kara can deduce her current state from, but it’s makes her stomach warm to think of how well Kara actually knows her. It’s comforting to know there is another person - human or not - on this planet that understands her so deeply, so uniformly, that it’s as if they’re a part of her, too.

And Alex knows - she knows more than anything - knows it to be truer than any law of science or math or any other unequivocal fact - 

For as long as Alex has been Kara’s, Kara has also been Alex’s. 

“You’re mine,” Alex croaks into the soft fleshy part of Kara’s neck where two days prior she had sunk her teeth in until Kara’s moans turned to whimpers and her legs parted with broken pleas, “and I love you.”

“I know I am,” Kara whispers against the top of her head, arms wrapped tightly around her. “I love you too.”

Alex shouldn’t, not when she’s so upset, but she can’t honestly help herself when she tilts her head up, seeking out Kara’s lips. There are worse moments and situations to seek out such physical comfort, she tells herself. She’s not a bad person for sighing when Kara kisses her back, for allowing herself to be pressed into the length of her couch with Kara’s naked body resting on top of her. She’s simply human.

And Alex remembers, when Kara’s lips are on her neck, teeth scraping against the sensitive skin, what Kara had said two nights prior, “Wait - stop. Wait. Kara. Hold on.”

“What?” Kara’s eyes are dark, lips red and wet, and cheeks flushed with want. “Did I hurt you?”

“No. The other night - you said Maggie was human. We were fighting. What did you mean? _I’m_ human,” Alex tries to put the thoughts into words, but all she can think is _she’s a human, Alex, and you’re mine_.

Kara smiles, nuzzles Alex’s cheek before depositing a soft kiss there. “I know. But you’re my human. It’s different.”

There’s a fluttering in her heart that Alex is afraid Kara can somehow hear. “But what did you mean?”

“Krypton was a bit different,” Kara says with a sigh, shifting her weight off of Alex a bit until Alex frowns and tugs her back down by her hips. “Monogamy is a staple here on Earth for most humans, and I thought if you married her then I’d never - you wouldn’t be mine anymore. You’d be giving yourself to her. And I wanted you to give yourself to _me_.”

“I don’t think I’ve given myself more to anyone but you,” Alex manages a small smile, her eyes fluttering when Kara gently brushes the tears from her face. “You idiot.”

“Can I take you to bed?” Kara asks against her lips, a soft pattering of words that make Alex shiver.

“I think - can we just lay here?”

Kara immediately shifts to the side, pulling Alex in tightly to her body with a soft, “Of course. Anything you want.”

Alex feels when Kara falls asleep, her naked body warm beside her, her breathing even and soft. Her hair tickles Alex’s cheek, and when she turns her head into Kara’s chest, Kara’s arms tighten around her. Alex’s sweater is suddenly too thick, her jeans too tight, but she can’t be bothered to wake Kara, to do anything to disrupt the sudden stillness that’s come over her.

Everything feel light and fuzzy, like she’s in a dream and on the verge of waking up, but Alex can’t fall asleep for the life of her. She drifts through consciousness with hardly a concrete thought in mind. She’s not sure how long they had been lying there when Kara shifts, presses a soft kiss to her head.

“Hello,” Kara mumbles against her her hair, sighing and dropping her face to Alex’s neck.

“Good nap?”

Kara nods, stretching her legs out before throwing one of them over Alex’s hip. “Yup. I love sleeping beside you. Did you sleep?”

“No, not really,” Alex says mournfully, and exhaustion licks at the edge of her nerves, making her feel heavy and dull.

“Oh.” Kara lifts her head from Alex’s body. “I’m sorry about Maggie. That’s why you were upset, right?”

Alex’s throat gets tight, too tight to force any words out, so she nods instead.

“I know - I know you really liked her. And I’m sorry I messed that up.” Kara drops her head down to nuzzle Alex’s nose with her own when she opens her mouth to protest. “But I’m _not_ sorry that we have this. I - it’s selfish of me, but I’ve wanted it for so long. And now I have it - we have it. I wouldn’t trade it for anything.”

Sniffling, Alex offers her a tender smile. “Me neither.”

“You’re not a bad person, you know. For wanting this. Or me,” Kara says, cutting straight to the core of Alex’s guilt. “I think something like this, it’s just unstoppable. Maggie’s nice. She gets that.”

“She shouldn’t have to,” Alex mutters. She cuts her eyes to the cable box, the neon green numbers flashing the time brightly across the room. “She’s at work right now. Dealing with this. I have you. Who does she have?”

“She still has you, Alex. Give her time.” Kara presses a short, sweet kiss to Alex’s lips. “Stop beating yourself up. This will get better, I promise.”

“How do you know?” Alex asks, desperation hanging to every word.

“I just do.”

For a moment, that’s not good enough for Alex. She hurt Maggie, potentially losing a good friend in the process, and the guilt that weighs heavily on her shoulders will be there for a long time, that Alex is sure of. But Alex thinks of all the times throughout her life she’s reassured Kara of her strengths, saved her from her own fears, and loved her through her own guilt and loneliness. All with two simple words. How quickly those words turn the world on its axis, creating content where there should be none. 

“You’re mine,” Alex says. 

When Kara kisses Alex, holding her face delicately in her hands, it’s as if she’s trying to say those words back through sheer emotion. “I’m yours,” Kara says against her lips.

Everything _will_ be okay, Alex knows, so long as she is Kara’s and Kara is hers.


End file.
